1. Field of the Invention
This invention relates to the molding of a one-piece shoe from a plastic material such as polyurethane. A mold is provided having an internal cavity corresponding to the outer surface of the shoe and a last positioned within the cavity having a shape corresponding to the inner surface of the shoe. The last is mounted on a movable pivot so that the last can be moved and then rotated to permit removal of the molded shoe.
2. Brief Description of the Prior Art
Shoe manufacturing has traditionally been a labor intensive industry. In addition the most commonly used natural materials have steadily increased in price. These factors have caused a migration of shoe manufacturing facilities into areas of lower labor costs and at the same time have increased the economic advantages in the use of man-made materials. Shoes of various sorts have been made from materials such as rubber, vinyl, polyurethane, and the like. Neither the fabrication of such materials by the traditional shoe manufacturing methods or the molding of an entire shoe has met with widespread acceptance other than for specific and limited applications. There are a variety of causes: lack of permeability to air and water vapor, inability to conform to the shape of a foot different from the last on which the shoe was made, appearance, and cost. The present invention represents a significant improvement in appearance and a reduction in cost, particularly for open-toe shoes for women and children.
Many of the man-made materials such as vinyl and rubber compounds do not faithfully duplicate the fine details of a mold cavity. Polyurethane, however, is capable of replicating a mold surface with such fidelity that it is difficult by visual examination to differentiate between a polyurethane molded article and one made from natural materials. This characteristic of polyurethane has both advantages and disadvantages. Its advantage, of course, is that shoes can be made to meet the exacting requirements of the feminine shopper interested in style, appearance, and quality. But, such a molded polyurethane shoe also faithfully reproduces any defects in the mold and also renders parting lines of the mod most apparent in the final product.
Earlier methods of molding shoes made use of multi-piece molds of four or more pieces and which generated a multiplicity of parting lines on the shoe giving an immediate visual indication of the process by which the shoe was manufactured and thus reducing the commerical desirability. It is an object of the present invention to overcome many of these disadvantages and to provide a popular price shoe with such quality and appearance that it can compete successfully with more expensive shoes made by other methods.